1. Field of the Invention
The present invention relates to a lubricant composition. More specifically, the present invention relates to a lubricant composition which contains a condensate having a specific structure, and has excellent lubrication properties in rigorous conditions such as a high temperature and/or a high pressure.
2. Description of the Related Art
In general, a lubricant contains base oil and various additives. Examples of the base oil include mineral oil obtained from crude oil, ester-based oil which is chemically synthesized, fluorine-based oil, poly a olefin-based oil, and the like. Among them, the ester-based oil is preferably used in a jet plane, automobile engine oil, grease, and the like from the viewpoint of a low pour point, a high viscosity index, a high ignition point, excellent lubrication properties, biodegradability, and the like.
Various esters such as monoester obtained from a reaction between an aliphatic monocarboxylic acid and monohydric alcohol; diester obtained from a reaction between an aliphatic dibasic acid and monohydric alcohol; ester obtained from a reaction between polyhydric alcohol and an aliphatic carboxylic acid; and composite ester obtained from a reaction between polyol, a polybasic acid, and an aliphatic monocarboxylic acid, have been disclosed as the ester-based oil (JP2002-097482A, JP2005-154726A, JP2005-232434A, JP2005-213377A, JP2005-232470A, JP2001-501989A, JP2001-500549A, JP2001-507334A, and JP2011-89106A).